The present invention relates to field devices for use in industrial processes. More specifically, the present invention relates to transmitters used to transmit process variables to monitor or control such an industrial process.
Generally, electronic field devices (such as process transmitters) are used to monitor the operation of industrial processes such as those in oil refineries, chemical processing plants, paper processing plants, biotechnology plants, pharmaceutical plants, food and beverage plants, and the like. Process transmitters for monitoring an industrial process may measure pressure, flow rate, fluid or material level in a tank, temperature, vibration, and the like. Additionally, such field devices may include analytical electronics, diagnostic electronics, or other process monitoring electronic devices, or even electronic, hydraulic or pneumatic actuator devices used for industrial process control.
Process transmitters are typically positioned within the processing plant in locations where liquids, dust and humidity and various industrial contaminants may be present. In some environments, process liquids such as acid solutions or base solutions can be present. Liquids may also include spray from hoses used to clean plant equipment. Liquids can drip, splash or spray onto the process transmitter and its electrical connections. Additionally, dust, humidity, and liquids in the environment may contaminate and degrade the electrical connections to and within the process transmitter.
In order to protect circuitry within the transmitter, the transmitter housing typically provides a seal against the local environment. This seal can be configured to meet explosive protection standards in order to reduce the likelihood of ignition of combustible materials. One transmitter configuration which illustrates an internal barrier is shown and described in U.S. Pat. No. 6,089,097, issued Jul. 18, 2000 to Frick et al.